The color blue has meant a lot of things to a lot of different people. In medieval times, the Virgin Mary's cloak was often painted a celestial, pure, sacred blue. In the early 1900s, Pablo Picasso created somber blue paintings during a period of depression. The color has been championed by everyone from jazz musician Miles Davis and singer-songwriter Joni Mitchell to the theatrical Blue Man Group.

Back in Colonial America, blue meant indecent. Lawmakers established rigid controls over morals and conduct; the so-called "blue laws" were designed "to encourage people to go to church, and to prohibit people from engaging in secular activities," says David L. Hudson Jr., an author and attorney who teaches about the first amendment at Vanderbilt University and the Nashville School of Law. The idea behind blue laws was to make certain activities illegal on Sundays.

"Fiddle players would often ... people would gather around and listen to them and drink and carouse and engage in activity that was not akin to sitting in a pew," says Hudson.

But why blue? Here's one theory: "The colony of New Haven printed their laws on blue sheets of paper," Hudson explains.

Sacrebleu!

Blue paper is also behind what's known as blue humor — jokes considered indecent or off-color. John Kenrick, who teaches the history of musical theater at New York University, says the term began 100 years ago, with performers working for the Keith-Albee vaudeville chain. After their first gig in each new theater, they would get notes written on blue stationary.

"That blue envelope was the management informing you what material in your act might be offensive to local audiences, and therefore had to be removed from your act on pain of termination," says Kenrick. "Over the course of time, blue came to be identified for any kind of humor that was off-color, that was a little too adult, that was risqué or even downright dirty."

In the early days of vaudeville, performer Sophie Tucker snuck some "blue" into her act with bawdy songs and stage shows. Comedian Milton Berle even found blue envelopes in his mailbox. The idea of blue meaning forbidden, adult, humor worked its way into Hollywood, and became a standard show business term.

"It was used in all areas of the business," says Kenrick. "So if you said something was blue, it meant it was dirty, it had to go."

Kenrick says Bob Hope loved telling dirty jokes in his burlesque career and in his private life, but was constantly censored on radio and TV. By the 1960s, though, comedian Redd Foxx's blue humor made it onto vinyl.

"Foxx was known for his incredibly adult humor," Kenrick says. "When these recordings did get done, they were carefully sold in the back of the record store, kind of like adult videos are in some stores today. 'Party records,' as they were known. And right in through my childhood in the '60s, there'd be a point where the grown-ups would put the kids to bed, they'd turn the volume down low and put on these adult party records. And that was where the blue humor got spread around."

These irreverent jokes were hip, Kenrick says.

"It's cool to be blue," Kenrick says. "It's cool to be off-color. It is outside of the norm. It's cool to challenge the establishment."

Singing The Blues

Blue also can evoke a deep sadness — as in "feeling blue." No one is exactly sure where that phrase comes from. Some say it dates back to the 16th century. Others have attributed it to the nautical practice of flying a blue flag or painting a blue stripe around the hull of a ship after the death of a captain or officer. Naturalist John James Audubon even wrote in an 1827 journal entry that he "had the blues" (though maybe he was talking about blue jay specimens).

The music that came to be called the blues originated in the plantation work songs of African slaves in the Mississippi Delta in the 1800s.

Folklorist Alan Lomax traveled the South recording this music throughout the 20th century. In his 1979 documentary, The Land Where The Blues Began, Lomax said the music was created out of loneliness and deprivation.

"As one old-times blues man told me: It'd take a man that had the blues to sing the blues," said Lomax. "And so the blues were born — field hollers floating over solid syncopated dance rhythms, songs that voiced unspoken anger, the powerful bitter poetry of a hard-pressed people."

But the name, the blues, may have its roots in another feeling besides sadness, says guitarist Debra Devi, author of the book The Language of the Blues.

"There was a phrase 'the blue devils,' which was used to mean the hallucinations that would bedevil somebody who had the [delirium tremens] from alcohol withdrawal," she says.

But Devi also offers another thought as well: "In West African culture — in Yoruba, specifically — there's a quality called coolness: Itutu, and it's symbolized by the color blue. And to have that quality means to be connected to the divine. This is a concept that came over with the Africans who came over here as slaves, and the color blue is used in Yoruban art to symbolize that quality."

Divine, soulful, cool, sad, naughty — it's a lot for one word to embody. Then again, the color blue comes in many shades.

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ROBERT SIEGEL, HOST:

In art, the color blue has many meanings. In medieval times, the Virgin Mary's cloak was always painted blue, a sacred color - celestial, pure. In the early 1900s, the artist Pablo Picasso created his somber blue paintings when he was depressed. As we continue our series on color, NPR's Mandalit Del Barco explains that blue has been associated with a lot of different moods and feelings.

MANDALIT DEL BARCO, BYLINE: Let's start with one meaning of blue - indecent. In colonial America, lawmakers established rigid controls over morals and conduct, regulations that were called blue laws.

DAVID L. HUDSON JR.: To encourage people to go church and to prohibit people from engaging in secular activities.

DEL BARCO: David L. Hudson, Jr. teaches about the First Amendment at Vanderbilt University in the Nashville School of Law. He says the idea behind blue laws was to make certain activities illegal on Sundays.

HUDSON: The colony of New Haven printed their laws on blue sheets of paper.

DEL BARCO: Blue paper is also behind what's known as blue humor, also considered indecent or off-color. John Kenrick, who teaches musical theater history at the New School and New York University, says the term began a hundred years ago with performers contracted by the Keith-Albee vaudeville chain. After their first gig in each new theater, they would get notes written on blue stationery - blue, which stood out.

JOHN KENRICK: That blue envelope was the management informing you what material in your act might be offensive to local audiences and therefore had to be removed from your act on pain of termination. Over the course of time blue came to be identified for any kind of humor that was off-color, that was a little too adult, that was risque or even downright dirty.

(SOUNDBITE OF SONG, "HE HADN'T UP 'TIL YESTERDAY")

SOPHIE TUCKER: I'm going to show him in the parlor why a girl turns out the lights.

DEL BARCO: In the early days of vaudeville, performer Sophie Tucker tried to sneak past the blue laws with her bawdy songs and stage shows.

(SOUNDBITE OF SONG, "HE HADN'T UP 'TIL YESTERDAY")

TUCKER: Now I'm determined to make him give in. I'm just crazy to have him begin.

DEL BARCO: The idea of blue meaning forbidden adult humor worked its way into Hollywood and became a standard showbiz term.

KENRICK: It was used in all areas of the business so if you said something was blue, it meant it was dirty, it had to go.

DEL BARCO: Kenrick says Bob Hope loved telling dirty jokes in his burlesque career and in his private life, but was constantly censored on radio and TV. By the 1960s, though, Redd Foxx's blue humor made it onto vinyl.

(SOUNDBITE OF ARCHIVED RECORDING)

REDD FOXX: I used to sing with the group. You remember the Ex-Lax Brothers? We had a big hit back in '58. I forget the words, but it started off doo doodle doo doo. Doo doodle doo doo. Oh, baby, doo doo. Don't laugh, it was number two all over the country.

(LAUGHTER)

KENRICK: When these recordings did get done they were carefully sold in the back of the record store, kind of like adult videos are in some stores today. Party records, as they were known, and right in through my childhood in the '60s there'd be a point where the grown-ups would put the kids to bed, they'd turn the volume down low and put on these adult party records. And that was where the blue humor got spread around.

KENRICK: It's cool to be blue. It's cool to be off-color. It is outside of the norm. It's cool to challenge the establishment.

DEL BARCO: But blue can also evoke a deep sadness, as in feeling blue. No one's exactly sure where that phrase comes from. Some say it dates back to the 16th century. Some have attributed it to the nautical practice of flying a blue flag or painting a blue stripe around the hull of a ship after the death of a captain or officer. Naturalist John James Audubon even wrote in an 1827 journal entry that he, quote, "had the blues" though maybe he was talking about Blue Jay specimens.

(SOUNDBITE OF SONG, "DEEP MOANING BLUES")

MA RAINEY: (Singing) I had the blues so bad that. I sit right down on my floor.

DEL BARCO: The music that came to be called the blues evolved from the plantation work songs of African slaves in the Mississippi Delta in the 1800s.

(SOUNDBITE OF UNIDENTIFIED SONG)

UNIDENTIFIED MEN: (Singing).

DEL BARCO: Folklorist Alan Lomax traveled the South recording this music throughout the last century. In his 1979 documentary "The Land Where The Blues Began," Lomax said the music was created out of loneliness and deprivation.

(SOUNDBITE OF DOCUMENTARY, "THE LAND WHERE THE BLUES BEGAN")

ALAN LOMAX: And so the blues were born - field hollers floating over solid syncopated dance rhythms, songs that voiced unspoken anger, the powerful, bitter poetry of a hard-pressed people.

DEL BARCO: But the name, the blues, may have its roots in another feeling besides sadness, says guitarist Debra Devi, author of the book "The Language Of The Blues: From Alcorub To Zuzu."

DEBRA DEVI: There was a phrase the blue devils, which was used to mean the hallucinations that would bedevil somebody who had the DTs from alcohol withdrawal.

DEL BARCO: But Devi also offers a slightly deeper definition.

DEVI: In West African culture - in Yoruba specifically - there's a quality called coolness - itutu - and it's symbolized by the color blue. And to have that quality means to be connected to the divine. This is a concept that came over with the Africans who came over here as slaves and the color blue is used in Yoruban art to symbolize that quality.